The present invention provides new methods and apparatus for use in a wellbore, particularly for supporting structures inside a tubular member within the wellbore. In addition to many other applications, the described methods and apparatus offer particular advantages when used within systems configured to repair damaged casing or other tubulars within a wellbore.
A number of different types of devices are known in the industry for use in supporting structures such as various tool strings within a casing or other tubular member disposed with a wellbore. For example, many types of hydraulically or mechanically actuated packers are known for such uses. However, in general, such packers will often be relatively expensive for many applications, such as those where the sole need is specifically to just physically support a structure within a casing or other tubular.
Similarly, many configurations of casing hangers are known that use moveable slip elements, similar to those on many packers, to engage the casing or other tubular. Again, casing hangers are often relatively complex and expensive for some applications. This can be particularly true where the intent is to secure a structure downhole where it will remain permanently. One example of such a use is where a repair assembly is to be put in place, such as to bridge across a section of damaged casing. As used herein, the term “damage” refers to any impairment of the capability of a casing or other tubular to form a reliable and impermeable conduit for well fluids. Thus, the term refers not only to such a tubular that has been subjected to specific harm resulting in such impairment, but also to such impairment that might occur through degradation such as that caused by corrosion or other degradation; and also as may occur through intentional breaching such as through perforations that are no longer desirable, such as where a zone has ceased producing desired fluids.
Recently, hangers have been proposed that are unitary devices that may be deformed such that the device will engage a casing sidewall. While such proposed devices offer the advantage of being less expensive than alternatives of the types noted above, they also suffer from the deficiency of having a relatively limited amount of deformation that is possible. These devices, therefore, may not be suitable for use where the casing dimensions are not known, or are not within an anticipated relatively limited range of tolerances for the anticipated casing type. Where the operable range of deformation is not adequate to fully span the gap between an acceptable nominal tool outer diameter and, for example, a somewhat oversized casing inner diameter from what is expected, such hangers may fail to adequately support the attached structures in the desired placement within the wellbore. This can lead to failure to achieve the intended purpose, and in some cases to costly retrieval or “fishing” operations to remove the structures from the wellbore.
Accordingly, the present invention provides new methods and apparatus for supporting structures within a casing or other tubular within a wellbore. In many embodiments, these apparatus can be of relatively simple construction, leading to relative ease and lower cost of manufacture; while at the same time offering an improved range of effective operation. Although such methods and apparatus are useful for a number of purposes, particular benefits are found in operations where the attached structures are intended to remain within the wellbore.